Exhaust and relief valve assembly

ABSTRACT

In a preferred form, a valve assembly including an inlet and an outlet. The valve includes an oscillatable, damped shaft and a cam operator member coupled thereto by unidirectional clutch means that couple the sleeve and shaft for concurrent movement in a first direction and decouples the sleeve with respect to the shaft on movement of the sleeve in a second direction. In a first control position, the cam operator conditions a valving element to an open position so as to communicate the inlet and outlet. In a second control position, the cam operator is positioned to maintain the valve closed. Further, in the second position, the valve includes means responsive to a predetermined pressure at the inlet to open the valving element independently of the cam operator so as to relieve the pressure buildup by communicating the inlet with the exhaust.

United States Patent [72] inventor George W. Jackson Dayton, Ohio [21]Appl. No. 827,427 [22] Filed May 23, 1969 [45] Patented July 13, 197173] Assignee General Motors Corporation Detroit, Mich.

[541 EXHAUST AND RELIEF VALVE ASSEMBLY 8 Claims, 11 Drawing Figs.

[52] U.S. Cl. 263/65 [5i] lnt.Cl F16f5/00 [50] Field of Search 267/65.650; l88/88.l

[56] References Cited UNITED STATES PATENTS 2,879,795 3/1959 Rossman263/65 (D) FOREIGN PATENTS 1,207,806 12/1965 Germany PrimaryExaminer-James B. Marbert Attorneys-W. Ev Finken and J. C. EvansABSTRACT: in a preferred form, a valve assembly including an inlet andan outlet. The valve includes an oscillatable, damped shaft and a camoperator member coupled thereto by unidirectional clutch means thatcouple the sleeve and shaft for concurrent movement in a first directionand decouples the sleeve with respect to the shaft on movement of thesleeve in a second direction. in a first control position, the camoperator conditions a valving element to an open position so as tocommunicate the inlet and outlet. In a second control position, the camoperator is positioned to maintain the valve closed. Further, in thesecond position, the valve includes means responsive to a predeterminedpressure at the inlet to open the valving element independently of thecam operator so as to relieve the pressure buildup by communicating theinlet with the exhaust.

PATENTEOJUU men 3,592,458

SHEET 1 0F 3 ATTORNEY I i INVIEN'I'UR.

PATENTEDJULIBISYI 3592.458

SHEET 2 [IF 3 INVliN'l UR.

ATTORNEY EXHAUST AND RELIEF VALVE ASSEMBLY This invention relates tomechanically operated valve mechanisms and more particularly to amechanically operated valve that controls fluid flow between an inletand outlet in response to mechanical movement of an operating member andfurther in response to a predetermined pressure buildup at the inlet ofthe valve independent of positioning of the operating member.

One type of leveling system for maintaining a predetermined heightrelationship between the sprung and unsprung mass of the vehicleincludes an electric-motor-driven compressor that when energized willdirect high-pressure air into the control chamber of a pressurizablefluid spring component to support added vehicle load that wouldotherwise deflect primary spring components of the vehicle suspensionthereby to move the vehicle chassis below a desired predetermined levelheight relationship with respect to its ground-engaging suspensionsystems.

In order to control such a system, it has been proposed that when thevehicle chassis moves about the desired height relationship that aheight controller be included to dump highpressure air from the springcomponents to return the vehicle to a level position. ignited the heightcontroller is located on the fluid spring component as part of the fluidspring assembly to reduce the number of external fluid connections andto simplify installation of the fluid spring component and valving uniton a vehicle for use in an automatic leveling system.

The exhaust of high-pressure fluid from the springs followingenergization of the electric-motor-driven compressor is sensed by meansthat will terminate energization of the motor compressor. To initiate afurther leveling of the vehicle, it is necessary to close a mechanicallyoperated start switch mounted on the dashboard of the vehicle.

One problem with leveling systems of the aforementioned type is that theelectric motor, under conditions where the compressor is unable toproduce a fluid spring pressure to compensate for the deflection in theprimary springs of the suspension system, remains energized toconstitute a continual drain on the vehicle battery during vehicleoperation.

One object of the present invention, therefore, is to provide a heightcontroller for association with an automatic leveling system of the typethat includes an electrically motor driven compressor that isdeenergized by means responsive to exhaust of fluid from the fluidsprings following return of the vehicle chassis to a point'slightlyabove level, including; a single valve that serves the combined functionof fluid spring exhaust when the vehicle is in its over level positionfollowing electric motor energization and of fluid spring relief when amaximum pressure buildup occurs in the fluid springs and the vehicle isbelow level following a pump-up phase of electric motor energizationbecause the vehicle loading is greater than the uplifting correctivecapacity of the fluid springs.

A further object of the present invention is to provide a combinationheight sensing controller assembly having a valving component thereinwith a fill position and an exhaust position and wherein the valve isassociated with means for operating it to the exhaust position on eitherthe occurrence of a predetermined height relationship between the sprungand unsprung mass of a vehicle and/or a predetermined maximum pressurebuildup within a fluid spring component of a vehicleleveling system.

Another object of the present invention is to provide a heightcontroller for an automatic leveling system of the type having anelectrically motor driven compressor selectively energized to vary thepressure in a fluid spring that assists a primary spring component of avehicle suspension and wherein the height controller includes a dampedoperated shaft having a sleeve slidably rotated and supported thereonthat is coupled to the shaft on movement of the sleeve in a firstdirection of rotation and decoupled from the shaft in an oppositedirection of rotation so as to cause an associated valve mechanism ofthe controller to bedamped against normal road movement oscillationsbetween the sprung and the unsprung mass of a vehicle and to closewithout delay when additional static loading is placed on the vehicle.

Another object of this invention is to provide a mechanically operatedheight controller that is adapted to be connected directly to a wallportion ofa fluid spring in a vehicle leveling system and wherein theheight controller includes means for exhausting fluid from the springeither following leveling of the vehicle or when the fluid springcomponent has a predetermined maximum pressure building therein; theheight controller including a single valve and means to operate thevalve so as to be damped against ordinary road movements of the vehicleand to be closed without delay when static loading is added to thevehicle.

In one working embodiment of the present invention, the aforesaidobjects and others are attained by including a controller housing withan inlet and outlet. An oscillatable operating shaft within thecontroller has one end thereof connected to a motion damper. A sleeve isslidably rotatably supported on the operating shaft and is directlycoupled thereto by a spring clutch when the sleeve is oscillatedrelative to the shaft in a first direction. In the opposite direction ofrelative movement between the sleeve and the shaft the spring is unwoundto decouple the sleeve from the damper.

The controller includes a bore therethrough which has a valve locatedtherein on a movable carriage. The valve has an elongated stem whichconnects to a spring-biased cam follower that is reciprocated within thebore by a cam ramp on the sleeve. The sleeve also has an outwardlydirected finger that is held by spring means against a part of the fluidspring that is relatively movable with respect to that portion of thefluid spring on which the controller housing is located. When the fingeris in a first operating position, that represents a height relationshipbetween the component parts of the fluid springs corresponding to thesprung mass of the vehicle being below level, the valve is closed toprevent exhaust of fluid from the fluid spring. When the vehicle sprungmass is moved or located above level by virtue of a change in the staticloading thereon the cam ramp and follower will be positioned to causethe valve to open and exhaust the fluid springs to level the vehicle.

When the vehicle spring mass is too heavily loaded and is located belowa predetermined level point to produce a maximum pressure buildup in thefluid spring components a movable piston that carries the valve isshifted to cause a second end portion on the operating stem of the valveto engage a valve operator and thereby cause the valve to be conditionedto open and exhaust the fluid spring to relieve the pressure builduptherein caused by the overload condition.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawings wherein preferred embodiments of the present invention areclearly shown.

FIG. I is diagrammatically shown in view ofa vehicle having a levelingsystem that includes the height controller of the present invention;

FIG. 2 is an enlarged, fragmentary, sectional view of the controller inassociation with a combination shock absorber and air spring device;

FIG. 3 is a vertical sectional view taken along the line 3-3 of FIG. 2looking in the direction of the arrows;

FIG. 4 is a fragmentary side elevational view looking in the directionof the arrows 4 in FIG. 3;

FIG. 5 is a horizontal sectional view taken along the lines 55 of FIG. 3looking in the direction ofthe arrows;

FIG. 6 is a vertical sectional view like FIG. 3 showing the valve in itsopen position;

FIG. 7 is a view in vertical section like FIG. 3 showing the valve ofthe controller in a high-pressure relief position;

FIG. 8 is an enlarged vertical sectional view of an operator cam in thecontroller of FIGS. 1-7;

FIG. 9 is an enlarged fragmentary sectional view of another embodimentof the height controller of the present invention;

FIG. is a vertical sectional view taken along the line 10-10 of FIG. 9looking in the direction of the arrows; and,

FIG. 11 is an enlarged vertical sectional view of an operator cam in theembodiment of FIGS. 9 and 10.

Referring now to the drawings, in FIG. 1 a pump-up-type open loop,semiautomatic leveling system 10 is illustrated in association with avehicle having a chassis with a lower frame 12. In the illustratedarrangement, the lower frame 12 is associated with a rear suspensionassembly 14 having an axial housing 16. On the opposite ends of thehousing 16 are tire and wheel assemblies 20, 22.

The rear suspension assembly 14 constitutes an unsprung mass of thevehicle on which is supported the lower frame 12 which constitutes asprung mass of the vehicle.

More particularly, in the illustrated arrangement a primary suspensionspring 24 resiliently supports one side of the frame 12 from theassembly 14 and on the opposite side thereof a primary suspension spring26 performs the same function.

Associated with the spring 24 is an auxiliary load supporting device 28that includes a hydraulic shock absorber 30 having its bottom end mountconnected by a pin 32 to a control arm 34.

The upper end of the shock absorber 30 is connected to a bracket 36offthe frame 12.

A pressurizable fluid spring 38 of the assembly 28 is pressurizedthrough a crossover tube 40 that communicates with the control chamberof a fluid spring 42 of an auxiliary load supporting device 44 that alsoincludes a hydraulic shock absorber 46.

The shock absorber 46 has its bottom end mount connected by a pin 48 toa control arm 50. The upper end of the shock absorber 46 is secured to abracket 52 that is fixedly secured to the side of the lower frame 12opposite bracket 36.

In the illustrated arrangement, an electric motor 54 drives a compressor56 which has an inlet connected to atmosphere and an outlet connectedthrough a high-pressure supply conduit 58 to an inlet fitting 60 to thecontrol chamber of fluid spring 42.

On the side of the fluid spring 42 there is located a controller 62 thatis selectively operated, in accordance with principles of the presentinvention, to control the exhaust of fluid from both the fluid spring 38and fluid spring 42 to an exhaust conduit 64 that communicates with apressure operator 66 that operates a control switch 68 for controllingenergization of the motor 54. When fluid is dumped to the pressureoperator 66, the motor is off.

An outlet 70 from the pressure operator 66 includes a spring biased ballcheck valve element 72 that serves as-a primary dump path for fluid fromthe assemblies 28, 44 during an exhaust phase of operation.

In the illustrated arrangement, the motor and compressor are locatedwithin a canister 74 to protect them against damage. The details of theaforedescribed semiautomatic leveling system 10 are merelyrepresentative of one arrangement that is improved by use of the heightcontroller of the present invention.

Referring now more particularly to FIG. 2, the auxiliary load supportdevice 44 is seen to include a rigid outer wall or dust shield 75 at theupper end thereof which connects to a threaded stud 76 that is fixedlysecured to the bracket 52. The dust shield 70 also connects to the upperend of a piston rod 77 which extends from the top 79 of the shockabsorber 46.

The dust shield 75 has its lower end fixedly connected to one end of aflexible sleeve element 78 by a clamp ring 80 defining a sealed joint.The sleeve 78 is turned inwardly on itself and has the opposite endthereof located against the outer circumferential surface of the shockabsorber 46 where it is secured by a clamp ring 82 to define anothersealed joint. Ac-

like fitting on the dust shield portion of the combination shockabsorber and air spring assembly 28. Assembly 28 has component partsidentical to those described above with reference to assembly 44. Theonly difference between the assembly 44 and the assembly 28 is the kindsof fluid fittings thereon that are clearly shown in FIG. 1.

Back to FIG. 2, it can be seen that the dust shield 70 includes a sideport 88 therein that defines an outlet from the control chamber 84 ofassembly 44 and also a path for exhaust of fluid from assembly 28through the crossover tube 40.

The controller 62 includes an outer housing 90 that is fixedly securedto spaced apart nuts 91 and 92 that are welded to the outer surface ofthe dust shield 75. The nuts 91, 92 receive screws 93, 94 respectivelyfor fastening the housing 90 in place on the dust shield 75.

The housing 90 further includes a side opening 96 which is aligned withthe side port 88. The opening 96 is formed in a curved surface 98 on thehousing 90 which is juxtapositioned with respect to the outer surface ofthe dust shield 75 and a continuously formed groove 100 in the surface98 has an annular seal element 102 therein maintained in sealingengagement with the dust shield to prevent fluid leakage from thecontrol chamber 84.

The side opening 96 leads to a chamber 104 having a bottom closureelement 106 at the base thereof secured to the housing 90 by fasteningscrews 108 which hold a gasket 110 between the closure element 106 andthe housing 90 to define a sealed fluid flow path to a housing bore 112which communicates with an exhaust fitting 114 threadably received andsupported within an upper end opening 116 in the housing 90. The fitting114 is sealed with respect to housing 90 by an O- ring seal element 118supported within a groove 120 in the end opening 116.

Oscillatable operating shaft 122 is located in a lower part of thechamber 104 as is best seen in FIG. 3. One end of the operating shaft122 is rotatably supported in a bearing 124 on the housing 90 and theopposite end thereof is directed through an opening 126 in the housing90 at which point it is rotatably supported by housing 90. The shaft 122includes an outwardly directed extension 128 thereon which is connectedto a generally circular damping disc 129 that overlies substantially thefull planar extent of a depression 130 that is formed in a side plate132 of the housing 90. The depression 130 in the plate 132 is closed bya cover 134 which is secured on the housing 90 by suitable fastenerssuch as screws 136 located about the outer periphery thereof.

A seal element 138 is located in an annular groove 140 formedcontinuously around the outer periphery of the plate 132 and it is heldin sealing engagement with the cover 134 to define a chamber 142 filledwith a suitable viscous damping fluid. The fluid also fills depression130 and thereby covers each face of the disc 129 so that movement of thedisc within the chamber 142 will produce a shear force resistancebetween the disc and the cover 134 and/or the plate 132 thereby to damprelative oscillations of the operating shaft 122 about its longitudinalaxis.

In the illustrated arrangement, the chamber 142 is sealed along theperiphery of the shaft 122 by an O-ring seal element 144 that is locatedwithin a peripheral groove 146 formed continuously around the operatingshaft 122 where it passes through the opening 126 in the housing 90.

A sleeve member 148 is slidably rotatably received on the operatingshaft 122 between the bearing 124 and the opening 126 in the housing 90.The sleeve member 148 includes a radially outwardly directed finger 150that is located within the chamber 104 so as to be moved with respect toand through the side opening 96 of the housing 90 and the side port 88in the dust shield 75. An angularly offset distal end 152 on the finger150 is located within the control chamber 84 so as to overlie the top 79of the shock absorber 46.

The finger 150 is biased in a counterclockwise direction as viewed inFIG. 1 by a coil spring 154 that is wound around a sleeve extension 156that is located on the member 148 adjacent the opening 126 in thehousing 90. The coil spring 154' includes an end segment 158 thereonthat engages the bottom closure element 106 and an end segment 160 thatis seated against the cam member 148.

The opposite end of the member 148 is coupled to the operating shaft 122through a spring clutch element 162 which serves to directly couple themember 148 to the operating shaft 122 when the member 148 is driven in acounterclockwise direction relative to the operating shaft 122 as isviewed in FIG. 2.

In the opposite direction of rotation, clockwise as viewed in FIG. 2,the spring clutch 162 is unwound from the outer periphery of theoperating shaft 122 whereby the element 148 is decoupled from the dampedshaft 122 so as to allow undamped movement of the finger 150 into thechamber 104 as viewed in FIG. 2.

Between the finger 150 and the extension 156, the element 148 has araised peripheral cam ramp 164 that increases in height in acounterclockwise direction as viewed in FIG. 2.

The ramp 164 engages a cam follower 166 that is slidably reciprocablyreceived within the housing bore 112. The cam follower 166 is morespecifically set forth in FIG. 5 as including a plurality ofcircumferentially located ribs 168 that serve to reinforce acontinuously formed outer peripheral wall 170 that slides against theinside of the bore 112. Between each of the reinforcing ribs 168 islocated a passageway or opening 172 that serves to communicate thechamber 104 with the bore 112 at a point above follower 116 so as todefine an exhaust path to a combination height control and relief valveassembly 174.

The assembly 174 includes a cylindrical carriage member 176 that isslidably adjustably received within the bore 112 above the cam follower166.

The carriage 176 includes a bottom opening 178 which is defined by aradially inwardly directed continuously formed flange seat 180. Theflange seat 180 supports the lower end of a movable piston element 182which is slidably reciprocably received within a bore 184 in thecarriage 176 immediately above the bottom opening 178 therein.

The piston 182 includes a peripheral groove formed continuouslytherearound at 186 in which is located an O-ring element 188 for sealingagainst leakage between the piston 182 and the carriage at bore 184.

A Schrader type valve 190 carried by the piston 182 includes a threadedcore 192 that secures the valve 190 in place within an internallythreaded head portion of the piston 182,

The valve 190 includes an operating stem 194 that has a valving element196 fixedly secured thereto normally spring biased by a return springinside core 192 (not shown) against a valve seat 198 on the base of thecore portion of the valve 190.

A stop member 200 on the bottom end of the operating stem 194supportingly receives a washer element 202 that is freely slidablc withrespect to the portion of the operating stem depending below the valvingelement 196. A coil spring 204 biases the washer 202 seated against themember 200.

The opposite or upper end of the operating shaft 194 includes a headportion 206 which is normally maintained in spaced relationship to theunderside of a setscrew 208 that is threadably received within athreaded interior 210 of a plug 212 that includes a radially outwardlydirected flange 214 on the upper end thereof seated on a continuouslyformed upwardly facing shoulder 216 on the upper end of the movablecarriage 174.

The flange 214 of the plug 212 is fixedly secured with respect to thecarriage 176 by a spun-over upwardly directed flange 218 on the carriage176. Openings 219 in flange 214 communicate the carriage interior withoutlet 114.

The flange 214 also serves as a seat for one end of an adjustment orrelief pressure spring 220 that has the opposite end thereofsupportingly received on an upper seat 222 on the piston member 182. t

The carriage 176 includes a peripheral groove 224 around the upper endthereof slightly below the flange 218 in which is received aneccentrically located tip 226 on an adjusting plug member 228 thatextends through a side opening 230 in the housing as is best seen inFIGS. 3 and 6. The plug member 228 has a flange 232 thereon locatedoutwardly of the opening 230 serving as a stop against axial movement ofthe plug member 228 into the bore 112. A slotted head 234 on the plugmember 228 is adapted to receive a tool for rotating it so as to shiftthe eccentrically located tip axially 226 upwardly and downwardly withinthe bore 112 thereby to cause a like movement of the carriage 176. Thecarriage 176 is slidably sealed within the bore 112 by an O-ring 236that is seated in an annular groove 238 in the periphery of the carriage176 adjacent the bottom flange 180 thereof.

Leakage from the bore 112 around the outer periphery of the adjustingplug 228 is sealed by an O-ring element 240 that is seated within theopening 230 against a shoulder 242 on the plug 228 located immediatelyaxially inwardly of the flange 232 As best seen in FIG. 4, the plug 228is held in its adjusted position by a bifurcate spring 244 that overliesthe flange 232 to be held in interlocking relationship therewith by asetscrew 246 having the head thereof against the outside surface of theelement 246 and the shank thereof threadably received in a tappedopening at the top of the housing 90.

In the illustrated semiautomatic leveling system the aforedescribedcontroller 62 produces a predetermined buildup of pressure in theauxiliary load supporting devices 28, 44 which reflects either oftwoconditions.

The first condition is when a load has been added to the chassis 12 andelectrical circuit means are conditioned to energize the motor 54 todrive the compressor 56 so as to discharge high-pressure air through thehigh-pressure discharge conduit 58 into the pressurizable controlchambers 84 of the assemblies 28, 44. When the added vehicle load isbelow a predetermined maximum value, the devices 28, 44 produce asupplemental resultant uplifting force on the lower frame 12 thatassists springs 24, 26 so as to move the frame 12 above a predeterminedheight relationship with respect to the rear suspension assembly 14.With the movement of the lower frame 12 above the desired predeterminedheight relationship the finger is moved interiorly of the controlchamber 84 and counterclockwise about the longitudinal axis of shaft 122as viewed in FIG. 2 to a point where a reduced height segment of thevariable height cam ramp 164 engages the cam follower 166. The spring204 biases the follower 166 in a direction to move it and the washer 202along with the operating stem 194 downwardly within the bore 112 so asto move the valving element 196 away from the seat 198 thereby to openthe valve as shown in FIG. 6.

As a result, a slight amount of high-pressure air is exhausted from thecontrol chamber 84 through the chamber 104 thence through the openings172 in the cam follower 166, the interior of the valve 174 thencethrough openings 219 in the flanged head 214 into the top of the bore112 from whence the pressurized fluid flows through the fitting 114 intothe exhaust conduit 64 thence to the pressure operator 66.

At this point, the switch 68 will be opened in the representa-. tivelyillustrated leveling system to open a circuit for energizing the motor54. As a result, the compressor 56 is shut down and a predeterminedbleed from fluid springs 38, 42 through outlet 70 occurs until the lowerframe 12 of the chassis returns to its desired predetermined heightrelationship with respect to the rear suspension assembly 14.

The return of the component parts of the vehicle to the desired heightrelationship is reflected in the position of the finger 150 on the camelement 148 with respect to the operating shaft 122. this position beingthat shown in solid lines in FIG. 2. During clockwise movement ofelement 148 the spring clutch 162 is unwound from the periphery of theshaft 122, hence following exhaust, return movement of the element 148is immediate and without damping.

In another phase of operation, the controller 62 includes means torelieve the leveling system 10 under conditions where the added vehicleload exceeds a maximum predetermined point.

Under these conditions the primary suspension springs 24, 26 along withthe auxiliary load supporting assemblies 28, 44 are unable to return thevehicle chassis to a desired predetermined height relationship withrespect to the rear suspension assembly 14.

Thus, the assemblies 28, 44 remain relatively collapsed and as a resultthe finger 150 of the element 148 tends to be rotated interiorly of thechamber W4. This causes the cam ramp 164 to have an increased heightsegment thereof in engagement with the cam follower 166 to cause it tomove upwardly within the bore 112 and thereby move the washer 202upwardly so as to compress the spring 204 as shown in FIG. 7. Anincrease in pressure within the control chambers 84 produced byoperation of the compressor 56 as well as the force of the spring 204acts on the underside of the piston rat to cause it to be moved upwardlyagainst the relief pressure spring 220. This will move the valve 190upwardly within the carriage 176 until the head 206 on the operatingstem 194 engages the adjustably located setscrew 203 within the plug212. As a result, the valving element 196 is moved away from the seat198 whereby excessive pressure buildup in the control chambers 84 isexhausted through a fluid path identical to that described with respectto the exhaust operation which occurs following movement of the vehiclechassis above the desired predetermined height relationship.

In accordance with other principles of the present invention, once thevehicle is leveled the damped operating shaft 122 will damp movement ofthe cam element 148 against high frequency load produced relativemovements between the dust shield 75 and the shock absorber 46 of theassembly 44. Accordingly, the valve assembly 190 remains closed duringsuch movement thereby to prevent an undesirable exhaust of fluid fromthe control chamber 84 other than during periods where the vehicle iseither overloaded or is moved above level in order to terminate motorenergization as discussed above.

More particularly, assuming that the vehicle has returned to level, thecam element 148 will be located as shown in FIGS. 2 and 3 to locate aheight segment of the cam ramp 164; with respect to the cam follower 166which will locate the operating stem 194 so as to maintain the valvingelement 196 in sealing engagement with the seat 198.

Transitory road induced vehicle movements that cause the opposite endsof the assembly 44 to move so as to cause top 79 of the shock absorber46 to move away from the dust shield 75 do not affect valve operation.MOre particularly, when the top 79 is moved away from the distal end 152a following movement of finger 150 will be delayed, since duringcounterclockwise movement, the element 148 is coupled to the dampedoperating shaft 122. Since the element 148 is directly coupled to theoperating shaft 122 the relative movement of the disc 128 within thefluid-filled chamber 142 will keep the cam element 148 in theillustrated solid line position of FIG. 2.

Transistory movements of the sprung and unsprung masses of the vehiclethat cause the top 79 of the shock absorber 46 to move upwardly withinthe dust shield 75 will momentarily shift the finger 150 into thechamber 104 to shift the cam ramp 164 so as to move the cam follower 166upwardly within the chamber 112. The valve 174 is decoupled from thefollower 166 during this movement and since there is no excessivepressure buildup in the control chamber 84 during this phase ofoperation, the valve 174 will remain closed to keep the control chambers84 of the assemblies 22, 44 inflated to a desired predetermined point.

in order to attain the aforementioned type of control during travel ofthe sprung mass above the predetermined height relationship, reliefvalve action when the system is overloaded, and damping action oftransitory road induced movements, the cam ramp 164 has a configurationas is illustrated in FIG. 8.

The shallow depth segment of the cam profile is indicated by referencenumeral 248 and the deep depth segment of the cam profile is indicatedby reference numeral 250.

The significant characteristics of the cam profile, in one workingembodiment of the invention that produces the aforementioned type ofoperation, is as set forth in the following schedule:

CAM PROFILE-FIGURE 8 In the associated system the mechanical andelectrical components have the following rating:

Component Rating Compressor 56 .136 cu. in. displacement. Motor 5t 5amps at 12 volts. Operating pressure of assemblies 28, 44 10125 p.s.i.g.

Another embodiment of the invention is illustrated in FIGS. 9 through 11as a controller 252; component parts of the controller 252 that areidentical to those illustrated in the controller 62 are designated withlike reference numerals primed.

The difference between the controller 252 and controller 62 is themanner in which the operating shaft 122 thereof is damped and the mannerin which a cam element 254 thereof is biased in a direction to couple itto the operating shaft 122'.

More particularly, as seen in FIG. 9, the cam element 254 includes anear formation 256 thereon which is in engagement with the top of aninverted hollow, open-ended piston element 258 that is slidablyreciprocably received within a depending cylindrical extension 260 on amodified base 262 that is secured to the housing by suitable fasteningmeans (not shown).

The piston 258 is biased outwardly of the cylinder 260 by a coil spring264 that serves the function of the torsion spring 156 in the firstembodiment. The spring 264 thus biases the piston 258 against the car256 of the cam element 254 so as to cause it to rotate in a directionwherein a clutch spring 266 will wind tightly on the end of theoperating shaft 122' whereby the cam element 254 and operating shaft122' will be damped by means including two discs 266, 268, each fixedlysecured to the end of the operating shaft 122 located within a slightlymodified damping chamber 270 formed between a disc cover 272 and arecessed opening 274 in the housing 90'.

As was the case in the first embodiment the chamber 270 is sealed by aperipheral seal element 138' located in a peripheral groove 140' in thehousing 90'. The cover 272 includes a central axially inwardly extendingsegment 276 which seats against the end of shaft 122 within the chamber270. This maintains a spaced relationship between the interior surface278 of the cover 272 and the disc 266. It also locates the disc 268 withrespect to the inside surface of chamber 270 formed by the recessedopening 274 in housing 90'.

Between discs 266, 268 is located a spacer 278. A viscous damping fluidsuch as a silicone fluid having a viscosity of 100,000 centistokes issheared between the surfaces of the discs 266, 268, spacer 278 and thewalls of chamber 270 to damp movement of the cam element 254 withrespect to the shaft 122 when the device is operated in accordance withthe present invention.

The operation of the device is identical to that described with respectto the controller 62 in the first embodiment. The damping is produced bya modified arrangement of parts and the biasing of the cam element 254so as to cause the finger in this embodiment to move against the topsurface of a shock absorber unit as previously described is modified inthe form of the biased piston 258 and the extension or ear segment 256on the cam element 254.

In this embodiment of the invention, the cam profile is as illustratedin FIG. 11 and includes the characteristics in the following schedule:

CAM PROFILEFIGURE 11 Inches X 102 X; 267 X; 203 H; 328 Hg 031 R 312 R381 R; 187 R, 342 D 562 The mechanical and electrical components of therepresentatively illustrated leveling system referred to in the firstembodiment also are found in systems used with the controller 252described in H68. 8 through 11. Their characteristics are the same asthose referred to with reference to the controller of the firstembodiment.

While the embodiments of the invention as herein disclosed constitutepreferred forms, it is to be understood that other forms might beadopted.

' What I claim is:

l. A height controller for controlling pressurization in a fluid springcomponent of an automatic leveling system for a vehicle having a sprungand an unsprung mass comprising; a housing having an inlet adapted to beconnected to the control chamber of a fluid spring component, an outletadapted to be connected to a low-pressure point in the system, valvemeans within said housing including a valve seat and a valve closureelement normally closed on said seat, an oscillatable member, springmeans for biasing said oscillatable member to follow movement of one ofthe vehicle masses to detect relative movement therebetween, means toopen the valve when the oscillatable member is positioned to indicate apredetermined raised height relationship between the sprung and unsprungmasses for exhaust fluid flow from the fluid spring through said inletand said outlet to the low-pressure point of the system, and meansindependent of said first means for opening said valve at apredetermined depressed height relationship between the sprung andunsprung masses that causes a predetermined maximum pressure within thefluid spring component thereby to allow relief fluid flow from the fluidspring component through said inlet and outlet ports of said housing.

2. A height controller for regulating pressure in a pressurized springcomponent in a leveling system for maintaining a desired heightrelationship between the sprung mass of a vehicle comprising; a housinghaving an inlet adapted to be in communication with a fluid springcomponent of a leveling system, an outlet in said housing adapted to beconnected to a low-pressure point in a leveling system, a housing borefluidly communicating said inlet and said outlet, a valve located withinsaid bore, means for supporting said valve for sliding movement relativeto said bore including a piston member having an end surface thereonexposed to the pressure at the inlet port, a relief pressure springbiasing said piston in a first predetermined direction within saidhousing bore against the pressure acting on said exposed end surface, ashaft, damping means connected to said shaft for producing apredetermined resistance to movement of said shaft about itslongitudinal axis, a sleeve member slidably received over said shaft,coupling means for connecting said sleeve member for concurrent dampedmovement with said shaft upon a first predetermined limited rotarymovement thereof, said coupling means allowing free relative rotationbetween said sleeve and said shaft upon movement of said sleeve in anopposite direction of rotary movement with respect to said shaft, firstvalve operator means responsive to damped movement of said sleeve in adamped direction to condition said valve when the vehicle is leveled toopen communication between said inlet and outlet for exhausting fluidfrom the fluid spring component, and second valve operator meansincluding an abutment member fixedly secured within said bore engageablewith said valve to open said valve when a predetermined pressure buildupoccurs on the exposed end surface of said piston and the sprung mass ofthe vehicle is below a desired predetermined heightrelationship with theunsprung mass to allow relief flow of fluid from the fluid springcomponent through said inlet and outlet.

3. A combination exhaust and relief valve assembly for controllingpressure within a fluid spring of an automatic leveling system toproduce a predetermined height relationship between the sprung andunsprung mass of the vehicle comprising; a valve housing having an inletport adapted to be connected to the pressure control chamber of a fluidspring component, an outlet port in said housing adapted to be connectedto a low-pressure point in the leveling system, a bore in said housingfluidly communicating said intake port with said outlet port, a valvelocated within said housing bore including an elongated operating stemarranged coaxially of the longitudinal axis of said bore, a pistonconnected to said valve, means for slidably supporting said pistonwithin said housing bore for relative reciprocal movement with respectthereto, a first valve operator located for relative movement withrespect to one end of said housing bore, means for moving said firstvalve operator within said bore in response to relative movementsbetween the sprung and unsprung masses of the vehicle, a second valveoperator fixedly located within said housing bore at the opposite endthereof, a first spring connected between said first valve operator andsaid piston to produce a first resultant force on said piston causing itto move toward said fixed operator, a second spring in the opposite endof said housing engaging said piston and producing a greater resultantforce on said piston than that of said first spring to prevent operationof said valve by said second operator during normal valving operation,said first valve operator being movable exteriorly of said housing boreduring an exhaust phase of operation and operative to engage said stemto lift said closure element from said seat to cause flow through saidvalve and exteriorly of said outlet port, means for damping relativemovement between said first valve operator and said housing bore whenthe vehicle masses have a predetermined height relationship, said pistonand valve being movable against said second spring upon the occurrenceof a predetermined maximum pressure in the fluid spring to cause saidstem to engage said second operator to lift said closure element fromsaid seat to relieve a predetermined maximum pressure buildup in thefluid spring when the sprung mass is located below a predeterminedheight relationship with said unsprung mass.

4. A height controller for controlling fluid flow between ahigh-pressure source and a low-pressure source in a system for levelingthe sprung and unsprung mass of a vehicle comprising; a housing havingan inlet and a outlet, an operating shaft journaled within said housing,means for damping limited rotation of said shaft about the longitudinalaxis thereof, a sleeve member slidably received on said shaft, means forspring biasing said sleeve for rotation with respect to said shaft in afirst predetermined direction, clutch means for connecting said shaft tosaid sleeve upon movement thereof in said first predetermined directionfor damping movement of said sleeve, said clutch means decoupling saidsleeve from said shaft upon movement of said sleeve in an oppositedirection of rotation with respect to said shaft for causing undampedmovement of said sleeve, a radially outwardly directed extension on saidsleeve adapted to oscillate about the longitudinal axis of said shaftbetween first and second positions in response to road movements ofvehicle, valve means interposed between said inlet and outlet having afirst position to open communication between said inlet and outlet and asecond position to close communication therebetween, means for operatingsaid valve means in response to movement of said sleeve member and forreturning said valve means to its second position without delay whensaid sleeve is moved in said opposite direction without damping.

5. A valve assembly for controlling fluid flow between a high-pressuresource and a low-pressure source comprising; a housing having an inletand an outlet, an operating shaft journaled within said housing, meansfor damping limited rotation of said shaft about the longitudinal axisthereof. a sleeve member slidably received on said shaft. means forspring biasing said sleeve for rotation with respect to said shaft in afirst predetermined direction. clutch means for connecting said shaft tosaid sleeve upon movement thereof in said first predetermined directionfor damping movement of said sleeve, said clutch means decoupling saidsleeve from said shaft upon movement of said sleeve in an oppositedirection of rotation with respect to said shaft for causing undampedmovement of said sleeve, a radially outwardly directed extension on saidsleeve adapted to oscillate about the longitudinal axis of said shaftbetween first and second positions, a housing bore, a cam surface onsaid sleeve, a follower element slidably supported within said bore andhaving a segment thereon in engagement with said cam surface so as toproduce reciprocal movement of said follower within said bore inresponse to oscillatory movement of said sleeve, hollow carriage membersupported within said bore in spaced relationship to said followerelement, a piston slidably reciprocably received within said carriagehaving an end surface thereon directly exposed to pressure at saidhousing inlet, a valve carried by said piston for movement therewithincluding a seat and a closure element normally closed when said sleeveextension is in its second position, means for coupling said follower tosaid valve to open said valve closure element following a predeterminedmovement of said sleeve in said first predetermined direction tocommunicate said inlet and outlet ports of said housing when said sleeveextension is in its first position, a relief valve spring biasing saidpiston into engagement with said carriage member when said sleeveextension is in its first position, a valve operator fixedly secured insaid bore in spaced relationship to said valve when said piston is sobiased against said carriage member, said piston being responsive to apredetermined pressure buildup when said sleeve extension is in itssecond position to shift against said relief valve spring to move saidvalve into engagement with said valve operator to relieve apredetermined pressure buildup at said inlet and allow flow offluidtherefrom to said outlet.

6. A valve assembly for controlling fluid flow between a high-pressuresource and a low-pressure source comprising; a housing having an inletand an outlet, an operating shaft journaled within said housing, asleeve member slidably received on said shaft, means for spring biasingsaid sleeve for rotation with respect to said shaft in a firstpredetermined direction, clutch means for connecting said shaft to saidsleeve upon movement thereof in said first predetermined direction fordamping movement of said sleeve, said clutch means decoupling saidsleeve from said shaft upon movement of said sleeve in an oppositedirection of rotation with respect to said shaft for causing undampedmovement of said sleeve, a radially outwardly directed extension on saidsleeve adapted to oscillate about the longitudinal axis of said shaftbetween first and second positions, a housing bore, a cam surface onsaid sleeve, a follower element slidably supported within said bore andhaving a segment thereon in engagement with said cam surface so as toproduce reciprocal movement of said follower element within said bore inresponse to oscillatory movement of said sleeve, hollow carriage membersupported within said bore in spaced relationship to said followerelement, means for adjustably positioning said carriage with respect tosaid housing bore and fixedly securing it in one ofa plurality ofadjusted positions, a stop shoulder on one end of said carriage definingan opening interiorly thereof, a piston slidably reciprocably receivedwithin said carriage having an end surface thereon directly exposed topressure at said housing inlet, a valve carried by said piston formovement therewith including a seat and a closure element normallyclosed when said sleeve extension is in its second position, means forcoupling said follower to said valve to open said valve closure elementfollowing a predetermined movement of said sleeve in said firstpredetermined direction to communicate said inlet asd outlet ports ofsaid housing when said sleeve extension is in its first position, arelief valve spring biasing said piston into engagement with saidshoulder when said sleeve extension is in its first position, a valveoperator fixedly secured in said bore in spaced relationship to saidvalve when said piston is so biased against said shoulder, said pistonbeing responsive to a predetermined pressure buildup when said sleeveextension is in its second position to shift against said relief valvespring to move said valve into engagement with said valve operator torelieve a predetermined pressure buildup at said inlet and allow flow offluid therefrom to said outlet.

7. A height controller for regulating the pressure within a fluid springcomponent of a vehicle leveling system for maintaining a predeterminedheight relationship between the sprung and unsprung masses of thevehicle comprising; a housin g having an inlet port and an outlet port,an oscillatable shaft located within said housing having one end thereofextending exteriorly of said housing, a damping element fixedly securedto said one end, means defining a fluid-filled chamber surrounding saidclamping element and cooperating therewith to produce a fluid damping ofoscillatory movement of said shaft about its longitudinal axis, a sleeveelement slidably received on said shaft for relative oscillatingmovement with respect thereto, a spring clutch element connected betweensaid sleeve element and said shaft and operative upon a firstpredetermined angular movement of said sleeve element with respect tosaid shaft to directly couple said sleeve element to said shaft to bedamped therewith during such movement, a finger on said sleeve extendingexteriorly of said housing adapted to follow movement of at least one ofthe sprung and unsprung masses for detecting relative movementtherebetween, a cam surface on the outer periphery of said sleeve, abore through said housing in fluid communication with said inlet andoutlet ports, a cam follower located within said bore for reciprocalmovement therein in response to oscillations of said sleeve elementabout the longitudinal axis of said shaft, a first spring for biasingsaid cam follower into engagement with said cam surface, a cylindricalcarriage located within said bore in spaced relationship to said camfollower, means for adjustably locating said carriage at a predeterminedfixed axial relationship with respect to said reciprocal cam follower, alongitudinal bore through said carriage, a piston slidably reciprocablyreceived within said carriage bore, a valve supported by said piston formovement therewith, said valve including a seat and a valve closureelement, an elongated operator stem secured to said closure elementhaving opposite ends thereon, said stern being arranged coaxially ofsaid carriage bore and having one end thereof located within said boreand the opposite end thereof extending within said housing bore in thedirection of said cam surface, a stop on said opposite end, a springseat supported by said stop and movable with respect to said stem in adirection away from said cam follower, a second spring having one endthereof in engagement with said piston and the op osite end thereofsupported by said seat, said second spring holding said seat againstsaid cam follower to cause said cam follower to open said valve forfluid flow thcrethrough when said cam surface is shifted to permitmovement of said cam follower outwardly of said housing bore during anexhaust phase of operation, a valve operating plug fixedly securedwithin said carriage bore for selectively engaging said one end of saidstem, a relief valve spring within said carriage bore for maintaining apredetermined force on said piston to prevent movement of said pistonand said valve toward said valve operating plug, said one end of saidstem being located between said piston and said operating plug andengageable therewith when a predetermined pressure is imposed on saidpiston to cause it to shift inwardly of said carriage bore against theforce of said relief valve spring to open said valve and thereby connectsaid inlet and outlet ports during a relief phase of valve operation.

8. in the combination of claim 5, said means for adjustably positioningsaid carriage including a side opening in said housing, a plug seatedwithin said side opening for limited relative rotation therein, meansfor sealing between said plug and said housing, said plug including aflange located exteriorly of said housing and in engagement therewith toprevent axially inward movement of said plug with respect to saidhousing opening, a slotted head on said plug located axially outwardlyof said flange, an extension on the opposite end of said plug sionwhereby upon rotation of said plug within said housing opening saidcylinder is reciprocated with respect to said housing bore, and meansfor locking said flange against rotation with respect to said housingwhen the cylindrical carriage located eccentrically of the longitudinalaxis of said plug. a member isin its adjusted Position slot in the sideof said carriage member receiving said exten-

1. A height controller for controlling pressurization in a fluid springcomponent of an automatic leveling system for a vehicle having a sprungand an unsprung mass comprising; a housing having an inlet adapted to beconnected to the control chamber of a fluid spring component, an outletadapted to be connected to a low-pressure point in the system, valvemeans within said housing including a valve seat and a valve closureelement normally closed on said seat, an oscillatable member, springmeans for biasing said oscillatable member to follow movement of one ofthe vehicle masses to detect relative movement therebetween, means toopen the valve when the oscillatable member is positioned to indicate apredetermined raised height relationship between the sprung and unsprungmasses for exhaust fluid flow from the fluid spring through said inletand said outlet to the low-pressure point of the system, and meansindependent of said first means for opening said valve at apredetermined depressed height relationship between the sprung andunsprung masses that causes a predetermined maximum pressure within thefluid spring component thereby to allow relief fluid flow from the fluidspring component through said inlet and outlet ports of said housing. 2.A height controller for regulating pressure in a pressurized springcomponent in a leveling system for maintaining a desired heightrelationship between the sprung mass of a vehicle comprising; a housinghaving an inlet adapted to be in communication with a fluid springcomponent of a leveling system, an outlet in said housing adapted to beconnected to a low-pressure point in a leveling system, a housing borefluidly communicating said inlet and said outlet, a valve locaTed withinsaid bore, means for supporting said valve for sliding movement relativeto said bore including a piston member having an end surface thereonexposed to the pressure at the inlet port, a relief pressure springbiasing said piston in a first predetermined direction within saidhousing bore against the pressure acting on said exposed end surface, ashaft, damping means connected to said shaft for producing apredetermined resistance to movement of said shaft about itslongitudinal axis, a sleeve member slidably received over said shaft,coupling means for connecting said sleeve member for concurrent dampedmovement with said shaft upon a first predetermined limited rotarymovement thereof, said coupling means allowing free relative rotationbetween said sleeve and said shaft upon movement of said sleeve in anopposite direction of rotary movement with respect to said shaft, firstvalve operator means responsive to damped movement of said sleeve in adamped direction to condition said valve when the vehicle is leveled toopen communication between said inlet and outlet for exhausting fluidfrom the fluid spring component, and second valve operator meansincluding an abutment member fixedly secured within said bore engageablewith said valve to open said valve when a predetermined pressure buildupoccurs on the exposed end surface of said piston and the sprung mass ofthe vehicle is below a desired predetermined height relationship withthe unsprung mass to allow relief flow of fluid from the fluid springcomponent through said inlet and outlet.
 3. A combination exhaust andrelief valve assembly for controlling pressure within a fluid spring ofan automatic leveling system to produce a predetermined heightrelationship between the sprung and unsprung mass of the vehiclecomprising; a valve housing having an inlet port adapted to be connectedto the pressure control chamber of a fluid spring component, an outletport in said housing adapted to be connected to a low-pressure point inthe leveling system, a bore in said housing fluidly communicating saidintake port with said outlet port, a valve located within said housingbore including an elongated operating stem arranged coaxially of thelongitudinal axis of said bore, a piston connected to said valve, meansfor slidably supporting said piston within said housing bore forrelative reciprocal movement with respect thereto, a first valveoperator located for relative movement with respect to one end of saidhousing bore, means for moving said first valve operator within saidbore in response to relative movements between the sprung and unsprungmasses of the vehicle, a second valve operator fixedly located withinsaid housing bore at the opposite end thereof, a first spring connectedbetween said first valve operator and said piston to produce a firstresultant force on said piston causing it to move toward said fixedoperator, a second spring in the opposite end of said housing engagingsaid piston and producing a greater resultant force on said piston thanthat of said first spring to prevent operation of said valve by saidsecond operator during normal valving operation, said first valveoperator being movable exteriorly of said housing bore during an exhaustphase of operation and operative to engage said stem to lift saidclosure element from said seat to cause flow through said valve andexteriorly of said outlet port, means for damping relative movementbetween said first valve operator and said housing bore when the vehiclemasses have a predetermined height relationship, said piston and valvebeing movable against said second spring upon the occurrence of apredetermined maximum pressure in the fluid spring to cause said stem toengage said second operator to lift said closure element from said seatto relieve a predetermined maximum pressure buildup in the fluid springwhen the sprung mass is located below a predetermined heightrelationship with said unsprung mass.
 4. A height controller forcontrollinG fluid flow between a high-pressure source and a low-pressuresource in a system for leveling the sprung and unsprung mass of avehicle comprising; a housing having an inlet and a outlet, an operatingshaft journaled within said housing, means for damping limited rotationof said shaft about the longitudinal axis thereof, a sleeve memberslidably received on said shaft, means for spring biasing said sleevefor rotation with respect to said shaft in a first predetermineddirection, clutch means for connecting said shaft to said sleeve uponmovement thereof in said first predetermined direction for dampingmovement of said sleeve, said clutch means decoupling said sleeve fromsaid shaft upon movement of said sleeve in an opposite direction ofrotation with respect to said shaft for causing undamped movement ofsaid sleeve, a radially outwardly directed extension on said sleeveadapted to oscillate about the longitudinal axis of said shaft betweenfirst and second positions in response to road movements of vehicle,valve means interposed between said inlet and outlet having a firstposition to open communication between said inlet and outlet and asecond position to close communication therebetween, means for operatingsaid valve means in response to movement of said sleeve member and forreturning said valve means to its second position without delay whensaid sleeve is moved in said opposite direction without damping.
 5. Avalve assembly for controlling fluid flow between a high-pressure sourceand a low-pressure source comprising; a housing having an inlet and anoutlet, an operating shaft journaled within said housing, means fordamping limited rotation of said shaft about the longitudinal axisthereof, a sleeve member slidably received on said shaft, means forspring biasing said sleeve for rotation with respect to said shaft in afirst predetermined direction, clutch means for connecting said shaft tosaid sleeve upon movement thereof in said first predetermined directionfor damping movement of said sleeve, said clutch means decoupling saidsleeve from said shaft upon movement of said sleeve in an oppositedirection of rotation with respect to said shaft for causing undampedmovement of said sleeve, a radially outwardly directed extension on saidsleeve adapted to oscillate about the longitudinal axis of said shaftbetween first and second positions, a housing bore, a cam surface onsaid sleeve, a follower element slidably supported within said bore andhaving a segment thereon in engagement with said cam surface so as toproduce reciprocal movement of said follower within said bore inresponse to oscillatory movement of said sleeve, hollow carriage membersupported within said bore in spaced relationship to said followerelement, a piston slidably reciprocably received within said carriagehaving an end surface thereon directly exposed to pressure at saidhousing inlet, a valve carried by said piston for movement therewithincluding a seat and a closure element normally closed when said sleeveextension is in its second position, means for coupling said follower tosaid valve to open said valve closure element following a predeterminedmovement of said sleeve in said first predetermined direction tocommunicate said inlet and outlet ports of said housing when said sleeveextension is in its first position, a relief valve spring biasing saidpiston into engagement with said carriage member when said sleeveextension is in its first position, a valve operator fixedly secured insaid bore in spaced relationship to said valve when said piston is sobiased against said carriage member, said piston being responsive to apredetermined pressure buildup when said sleeve extension is in itssecond position to shift against said relief valve spring to move saidvalve into engagement with said valve operator to relieve apredetermined pressure buildup at said inlet and allow flow of fluidtherefrom to said outlet.
 6. A valve assembly for controlling fluid flowbetween a high-pressuRe source and a low-pressure source comprising; ahousing having an inlet and an outlet, an operating shaft journaledwithin said housing, a sleeve member slidably received on said shaft,means for spring biasing said sleeve for rotation with respect to saidshaft in a first predetermined direction, clutch means for connectingsaid shaft to said sleeve upon movement thereof in said firstpredetermined direction for damping movement of said sleeve, said clutchmeans decoupling said sleeve from said shaft upon movement of saidsleeve in an opposite direction of rotation with respect to said shaftfor causing undamped movement of said sleeve, a radially outwardlydirected extension on said sleeve adapted to oscillate about thelongitudinal axis of said shaft between first and second positions, ahousing bore, a cam surface on said sleeve, a follower element slidablysupported within said bore and having a segment thereon in engagementwith said cam surface so as to produce reciprocal movement of saidfollower element within said bore in response to oscillatory movement ofsaid sleeve, hollow carriage member supported within said bore in spacedrelationship to said follower element, means for adjustably positioningsaid carriage with respect to said housing bore and fixedly securing itin one of a plurality of adjusted positions, a stop shoulder on one endof said carriage defining an opening interiorly thereof, a pistonslidably reciprocably received within said carriage having an endsurface thereon directly exposed to pressure at said housing inlet, avalve carried by said piston for movement therewith including a seat anda closure element normally closed when said sleeve extension is in itssecond position, means for coupling said follower to said valve to opensaid valve closure element following a predetermined movement of saidsleeve in said first predetermined direction to communicate said inletand outlet ports of said housing when said sleeve extension is in itsfirst position, a relief valve spring biasing said piston intoengagement with said shoulder when said sleeve extension is in its firstposition, a valve operator fixedly secured in said bore in spacedrelationship to said valve when said piston is so biased against saidshoulder, said piston being responsive to a predetermined pressurebuildup when said sleeve extension is in its second position to shiftagainst said relief valve spring to move said valve into engagement withsaid valve operator to relieve a predetermined pressure buildup at saidinlet and allow flow of fluid therefrom to said outlet.
 7. A heightcontroller for regulating the pressure within a fluid spring componentof a vehicle leveling system for maintaining a predetermined heightrelationship between the sprung and unsprung masses of the vehiclecomprising; a housing having an inlet port and an outlet port, anoscillatable shaft located within said housing having one end thereofextending exteriorly of said housing, a damping element fixedly securedto said one end, means defining a fluid-filled chamber surrounding saiddamping element and cooperating therewith to produce a fluid damping ofoscillatory movement of said shaft about its longitudinal axis, a sleeveelement slidably received on said shaft for relative oscillatingmovement with respect thereto, a spring clutch element connected betweensaid sleeve element and said shaft and operative upon a firstpredetermined angular movement of said sleeve element with respect tosaid shaft to directly couple said sleeve element to said shaft to bedamped therewith during such movement, a finger on said sleeve extendingexteriorly of said housing adapted to follow movement of at least one ofthe sprung and unsprung masses for detecting relative movementtherebetween, a cam surface on the outer periphery of said sleeve, abore through said housing in fluid communication with said inlet andoutlet ports, a cam follower located within said bore for reciprocalmovement therein in response to oscillatIons of said sleeve elementabout the longitudinal axis of said shaft, a first spring for biasingsaid cam follower into engagement with said cam surface, a cylindricalcarriage located within said bore in spaced relationship to said camfollower, means for adjustably locating said carriage at a predeterminedfixed axial relationship with respect to said reciprocal cam follower, alongitudinal bore through said carriage, a piston slidably reciprocablyreceived within said carriage bore, a valve supported by said piston formovement therewith, said valve including a seat and a valve closureelement, an elongated operator stem secured to said closure elementhaving opposite ends thereon, said stem being arranged coaxially of saidcarriage bore and having one end thereof located within said bore andthe opposite end thereof extending within said housing bore in thedirection of said cam surface, a stop on said opposite end, a springseat supported by said stop and movable with respect to said stem in adirection away from said cam follower, a second spring having one endthereof in engagement with said piston and the opposite end thereofsupported by said seat, said second spring holding said seat againstsaid cam follower to cause said cam follower to open said valve forfluid flow therethrough when said cam surface is shifted to permitmovement of said cam follower outwardly of said housing bore during anexhaust phase of operation, a valve operating plug fixedly securedwithin said carriage bore for selectively engaging said one end of saidstem, a relief valve spring within said carriage bore for maintaining apredetermined force on said piston to prevent movement of said pistonand said valve toward said valve operating plug, said one end of saidstem being located between said piston and said operating plug andengageable therewith when a predetermined pressure is imposed on saidpiston to cause it to shift inwardly of said carriage bore against theforce of said relief valve spring to open said valve and thereby connectsaid inlet and outlet ports during a relief phase of valve operation. 8.In the combination of claim 5, said means for adjustably positioningsaid carriage including a side opening in said housing, a plug seatedwithin said side opening for limited relative rotation therein, meansfor sealing between said plug and said housing, said plug including aflange located exteriorly of said housing and in engagement therewith toprevent axially inward movement of said plug with respect to saidhousing opening, a slotted head on said plug located axially outwardlyof said flange, an extension on the opposite end of said plug locatedeccentrically of the longitudinal axis of said plug, a slot in the sideof said carriage member receiving said extension whereby upon rotationof said plug within said housing opening said cylinder is reciprocatedwith respect to said housing bore, and means for locking said flangeagainst rotation with respect to said housing when the cylindricalcarriage member is in its adjusted position.